[llvm] [DXIL] Add GroupMemoryBarrierWithGroupSync intrinsic (PR #111884)

[Finn Plummer via llvm-commits]

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@@ -477,6 +500,11 @@ class OpLowerer {
     HasErrors |= replaceFunctionWithOp(F, OpCode);                             \
     break;
 #include "DXILOperation.inc"
+      case Intrinsic::dx_group_memory_barrier_with_group_sync:
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inbelic wrote:

I think we could also approach this as an intrinsic expansion. So we would create a DirectX intrinsic `dx_group_memory_barrier` that would lower here. Then we would deal with `dx_group_memory_barrier_with_group_sync` and all the other barrier ops as an intrinsic expansion with the applicable opcode and barrier modes.

I think that would be clearer when adding future barrier ops and match the flow of other intrinsics. WDYT?

https://github.com/llvm/llvm-project/pull/111884